Some small devices such as clocks require voltage that can be provided from a single cell or battery, which is typically 1.5 volts. However, most small battery powered devices now use two or more batteries arranged in a series electrical configuration to produce a higher voltage than is available from a single cell or battery. Past attempts to extend the operating time of battery powered devices used multi-battery receptacles which placed the batteries in a parallel electrical configuration. For example, U.S. Patent Application Publication No. US 2002/0036480 A1 to O'Neill et al. discloses a battery pack having two or more battery slots formed to receive standard-sized batteries in parallel electrical communication. However, there are problems associated with this configuration. If one or more batteries drain at a different rate than the other batteries in the circuit, then the batteries with the higher voltage will send current into the batteries with a lower voltage. The resulting reverse current will effectively charge primary batteries that are not designed to be charged. Reverse current through a primary battery may cause battery leakage, fire, and possibly even an explosion.
One prior method of addressing these deficiencies is to attempt to carefully match the multiple batteries to make sure each has similar characteristics in order to reduce the chance of voltage differences. Nonetheless, significant leakage can still occur, as well as fire and even an explosion. Another past attempt to prevent fire and potential explosion is to manufacture the batteries with internal fuses. Batteries with internal fuses may assist in resolving these deficiencies, but only as long as the each battery is not defective. If a battery is defective, and presents a low resistance as compared to other batteries in the circuit, then reverse current flow is likely to occur, and similar deficiencies will result.
In the past, diodes have been used within automobiles to isolate automotive batteries in multiple battery configurations. Multiple automobile batteries are typically used in electric and hybrid cars, as well as within some diesel trucks, for better cranking power on ignition. These arrangements are not applicable to smaller devices using multi-battery receptacles, and would present significant problems in implementation within smaller devices requiring multiple batteries for extended life of the device, and requiring little or no reduction in battery voltage.
The present invention is provided to solve these and other problems.